Description: (Applicant's Description) The use of genetically engineered mice has been growing exponentially. A recent study of the use of cell-knock-out mice by investigators at the Jackson Laboratory (Simpson, et al., Nature Genetics, 16:19, 1997), indicates that this use is continuing to grow; between 1988 and 1998, the number of publications utilizing knock-out mice is estimated to have grown from zero to well over 1,400. This is only a reflection of the power of the new technologies for the study of cancer, gene function, physiology, and human disease. However, because of the high cost and technical difficulties of establishing these procedures within individual laboratories, it is essential to support these technologies as a shared resource. This requires an efficient and cost-effective common facility that enables individual investigators to have both transgenic mice expressing genes of interest, and mice carrying gene knockouts created for them. The techniques available f rom this Resource place ground-breaking new power of analysis in the hands of our investigators. When used in combination with the other modern technical skills supplied by the Center's Animal Experimentation, Histology and Molecular Pathology facilities, it gives our investigators new opportunities to examine pathologic processes from several perspectives simultaneously. Our current facility has proven successful at enabling the creation of both transgenic mice and knockout mouse strains for multiple Cancer Center laboratories. Without such a centralized resource, most laboratories would not be in a position to utilize these powerful models, severely limiting the research and granting opportunities for our biomedical and cancer research community. Thus, the Transgenic Mouse Shared Resource of UCSD Cancer Center improves the quality, quantity and creativity of the research, while also enhancing cost-effectiveness and efficiency.